package com.lagou.edu.factory;

import com.lagou.edu.utils.TransactionManager;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

public class ProxyFactory {

    private TransactionManager transactionManager = TransactionManager.getInstance();

//    private TransactionManager transactionManager;
//    public void setTransactionManager(TransactionManager transactionManager) {
//        this.transactionManager = transactionManager;
//    }


    private ProxyFactory(){

    }

    private static ProxyFactory proxyFactory = new ProxyFactory();

    public static ProxyFactory getInstance() {
        return proxyFactory;
    }




    /**
     * Jdk动态代理
     * @param obj  委托对象
     * @return   代理对象
     */
    public Object getJdkProxy(Object obj) {

        // 获取代理对象
        return  Proxy.newProxyInstance(obj.getClass().getClassLoader(), obj.getClass().getInterfaces(),
                new InvocationHandler() {
                    @Override
                    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                        Object result = null;

                        try{
                            // 开启事务(关闭事务的自动提交)
                            transactionManager.beginTransaction();

                            result = method.invoke(obj,args);

                            // 提交事务

                            transactionManager.commit();
                        }catch (Exception e) {
                            e.printStackTrace();
                            // 回滚事务
                            transactionManager.rollback();

                            // 抛出异常便于上层servlet捕获
                            throw e;

                        }

                        return result;
                    }
                });

    }
}
